Optical System for Counting Objects

ABSTRACT

The invention comprises a system and an optical device ( 1 ) to facilitate the counting of objects, e.g. fish and other organisms living in freshwater or sea, especially when using large-scale equipment in fish-fanning. The system makes it possible to diminish the distance between the recording camera and the objects to be counted.

FILED OF THE INVENTION

The invention relates to a system and an optical device to facilitatethe counting of objects, e.g. fish and other waterborne organisms, inlarge-scale equipment used especially in fish-farming. The systemcomprises a camera, a light source and an array of mirrors that makes itpossible to diminish the distance between the recording camera and theobjects to be counted.

BACKGROUND OF THE INVENTION

In the fish-farming industry a common practice while transferringorganisms between receptacles is to make an estimation of the number andsize of organisms being transferred. Various methods are used to countthe organisms. As an example NO168151 (Kvassheim) discloses a method anddevice for the recording of number of objects, particularly live fish,were a CCD-line camera is used to count organisms on the basis of theirarea. NO332233 (Wingan) also discloses a fish counter where two camerasare positioned perpendicular to each other. None of these documentsdisclose a solution similar to the one described herein.

It is a commonly used technique when counting live fish in countingequipment for fish to position a camera between the stream of fish and alight source. The organisms then generate silhouettes that the cameraregisters. The signals from the camera are processed in a computer thatturns the data into information on the number of organisms by using aspecific algorithm.

When scaling up the size of equipment used in fish-farming industriesfor sorting and counting organisms it is a disadvantage that thedistance of the camera from the light source, as described above, has tobe enlarged in order for the camera to get a sufficient field of vision.The larger the equipment gets, the bigger the distance has to be.

SUMMARY OF THE INVENTION

As stated above, scaling up of devices for sorting and countingorganisms in fish-farming industries using imaging devices has thedisadvantage of increased distance of the camera from the light source,which demands more space and can result in less accurate counting. Theobject of the present invention is to overcome this disadvantage by aspecial optical device disclosed herein and a system for its use.

The invention relates to a system and an optical device to facilitatethe counting of objects, e.g. fish and other waterborne organisms, inlarge-scale equipment used especially in fish-farming. The systemcomprises a camera, a light source and an array of mirrors that makes itpossible to diminish the distance between the recording camera and theobjects to be counted.

It is an object of the present invention to overcome or ameliorate theaforementioned drawbacks of the prior art and to provide an improvedand/or alternative and/or additional method or device for counting fishand marine organisms. It is one preferred object of the presentinvention to provide a device with optical device and a light source inorder to further improve the failsafe and accurate operation, withincreased capacity with reduced space demands. Moreover, it is apreferred object of the present invention to provide a device comprisinga camera and a minimum of two mirrors which direct the camera field ofvision towards the light source that generates the silhouettes beinganalyzed. Another preferred object of the present invention is toprovide a device with an improved special construction of mirrors in thedevice which generates a line of sight that consists of multiplereflections with a certain angle. It is also a preferred object of thepresent invention to provide a device with an improved operabilityand/or an increased ease of use during operation and set up of thedevice. Preferably, only minor changes to the routine of the personnelare necessary. Also, it is one preferred object of the present inventionto avoid long setup times.

The object(s) underlying the present invention is (are) particularlysolved by the features defined in the independent claims. The dependentclaims relate to preferred embodiments of the present invention. Furtheradditional and/or alternative aspects are discussed below.

It is the combination of a) using a set of mirrors to shorten thedistance from the camera to the lane carrying the flow of livingorganisms and b) the broadened surface below the camera, which providesthe improved method and device resulting in more capacity of determiningnumbers or density of flow of living organisms in a fluid. Not only doesthe invention provide more capacity in counting or density measurementsof living organisms in a flow, but it also provides a more compactdevice as the distance from the camera to the in-feed channel can bereduced dramatically resulting in less space needed. The distance of thecamera from the in-feed channel needs to be larger when a broaderworking width is covered and some facilities do not allow such adistance. Furthermore, the combination of computer vision, the use ofmirrors to reflect the light from the in-feed lane, and the broadenedtransparent area of the in-feed lane to determine numbers or density offlow of living organisms in a fluid provides a more practical solutionto previous limitations in this field.

Thus, at least one of the preferred objects of the present invention issolved by an apparatus for determining density or number of livingorganisms. Preferably the apparatus comprises a channel for a flow ofliving organism, an outlet portion and a computer. The channel comprisesa flattened portion or lane made from transparent material and.Moreover, the apparatus preferably comprises a light source forprojecting light through a stream of living organisms, where the lightsource is positioned below the flattened portion or lane. The apparatusfurther comprises an optical device positioned above and directedtowards the flattened portion or lane of the channel, said opticaldevice is positioned behind at least two mirrors, which reflect thelight from the flattened channel or lane. Furthermore, the computerdetermines the density or amount of living organism in a flow based onthe amount of light reflected detected by the optical device. Preferablythe invention is based on using a minimum of one pair of mirrors.

In the present context, the ratio of the distance between the at leasttwo parallel mirrors and the total length of the field of vision,decreasing the distance of the field of vision outside the box, has tobe an even multiplier. This can be specified in the formula:

L 32 N*l+e ₁ +e ₂

where L is the total length and field of sight, N is an even multiplier(2, 4, 6, . . . ), l is the distance between the parallel mirrors, e₁ isthe distance from camera lens to the first parallel mirror and e₂ is thedistance from the last mirror reflection to the light source.

In the present context, the computer is used in combination with thecamera and the software to record silhouette images of the objectspassing by the light source, where an algorithm is used to recognize,filter and count the number of objects as they flow by.

Another preferred object of the present invention is solved by a methodfor determining density or number of living organisms in a flow, saidmethod comprising the steps of feeding a flow of living organism on achannel, the channel comprising a flattened channel or lane made fromtransparent material. Preferably, the method comprises the step of usinga light source for projecting light through a stream of livingorganisms, said light source is positioned below the flattened channelor lane and then feeding the flow of living organism trough an outletportion. The method further comprises the step of using an opticaldevice, positioned behind at least two mirrors, to reflect the lightfrom the flattened channel or lane. The optical device is positionedabove and directed towards the flattened channel or lane said opticaldevice is. Furthermore, the computer determines the amount of livingorganism in the flow based on the amount of light reflected detected bythe optical device.

Another preferred object of the present invention is solved by a fishfarm comprising an apparatus for determining density or number of livingorganisms in a flow. Preferably the apparatus comprises a channel for aflow of living organism, an outlet portion and a computer. The channelcomprises a flattened portion or lane made from transparent materialand. Moreover, the apparatus preferably comprises a light source forprojecting light through a stream of living organisms, where the lightsource is positioned below the flattened portion or lane. The apparatusfurther comprises an optical device positioned above and directedtowards the flattened portion or lane of the channel, said opticaldevice is positioned behind at least two mirrors, which reflect thelight from the flattened channel or lane. Furthermore, the computerdetermines the density or amount of living organism in a flow based onthe amount of light reflected detected by the optical device.

In an embodiment of the present invention, the optical device is acamera. In a specific embodiment of the present invention, the opticaldevice is a line-scan camera.

It is preferred to use a line scan camera but other kinds of camerascould also be used, such as frame cameras with the ability to extractsingle lines with a certain sampling rate to build a time series thatgenerate a continuous image.

It is preferred to use first-contact mirrors in the device to overcomethe attenuation and ghost shadows occurring using regular mirrors whichhave a layer of glass on top of the reflective surface. First contactmirrors have the reflective surface on the top of the surface and thusthe light does not have to travel through a layer of glass before beingreflected. The invention is not limited to the used of first-contactmirrors as regular mirrors or other kinds of mirrors may also be used.

In an embodiment of the present invention the at least two mirrors arefirst-contact mirrors.

In an embodiment of the present invention the flattened portion or laneof the channel made from transparent material has an open upper surface.

In an embodiment of the present invention the flattened portion or laneof the in-feed channel made from transparent material has a broadenedlower surface than the remaining part of the in-feed channel.

In an embodiment of the present invention, one or more of the channelfor a flow of organisms, the light source, the optical device and theoutlet are positioned within a housing. In a specific embodiment of thepresent invention the light source and/or the optical device arepositioned within a separate housing below and above the channel for aflow of organisms respectively.

In an embodiment of the present invention the living organisms comprisefish, smolt, crustaceans, shellfish or other organism living infreshwater or sea.

DETAILED DESCRIPTION OF THE INVENTION

The present invention will become more fully understood from thedetailed description given hereinafter and the accompanying drawingswhich are given by way of illustration only, and thus, are notlimitative of the present invention, and wherein:

FIG. 1 shows the top-view of a camera registering a stream of objectswithout the use of the optical device disclosed herein.

FIG. 2 shows the side-view of a camera registering a stream of objectwithout the optical device disclosed herein.

FIG. 3 shows the side-view of a camera with the optical device accordingto the invention situated between the camera and the objects to beregistered.

FIG. 4 shows the side-view of a cross section of the optical systemaccording to the invention showing the position of the main componentsand the line of sight.

FIG. 5 shows the top-view of the optical device.

FIG. 6 shows a three-dimensional view of the optical device.

In FIG. 1 the camera (1) is positioned at a certain distance to cover agiven width of the light source (4) which covers the actual width of thechannel in which the objects flow perpendicular to the plane of view.This angle of the camera optics and the channel width determines thedistance at which the camera needs to be positioned. The triangle (2)represents the field of view of the camera. The objects (3) to becounted flow freely by the light source (4), and create a shadow whenthey pass the light. This shadow is captured by the camera (1) and isregistered. This is also illustrated in FIG. 2 with a side view of theconstellation; camera (1), field of view (2), object (3) and the lightsource (4).

FIG. 3 shows the side view of the constellation of the new invention.The objects to be counted flow in a vertical direction. A pair of twoparallel mirrors (5) are lined up with the camera (1) and the lightsource (4) in such an angle that a certain number of reflections isachieved and the necessary physical distance between the camera (1) andthe light source (4) is reduced considerably still maintaining the fieldof view of the camera at the channel where the objects (3) flow past thelight source (4).

In FIG. 4 a side view of a cross section of an actual version of acounter is shown. The objects flow in a closed channel (6) acceleratingby the gravity force and pass the light source (4) where the visionfield (2) of the camera (1) captures the silhouette of the object. Thedirection of the field of vision (2) of the camera (1) is redirected bythe reflections of the mirrors (5) which are aligned and arranged in aposition to minimize the distance of the camera (1) when capturing thewhole width of the light source (4). A free opening (7) or gap traverseof the device is necessary to give a free sight for the field of vision(2) of the camera (1).

FIG. 5 shows a top view of the actual construction of the optical devicewhere the camera (1) is located at the center of the box and the fieldof vision (2) is represented by the diagonal lines running from thecamera (1) to the mirrors (5) forth and back.

FIG. 6 shows a 3-dimensional view of the actual construction of theoptical device as shown in FIG. 5 where the camera (1) is located at thecenter of the box and the field of vision is shown as (2) and he mirrorsas (5).

The invention is not limited to the above described implementations. Theinvention can be used to count various objects. One embodiment of theinvention is to count living organisms such as fish, smolt, crustaceans,shellfish or other organism living in freshwater or sea. Various kindsof mirrors may be used, e.g. first-contact mirrors but other kinds ofmirrors can also be used such as regular mirrors. Various kinds ofcameras such as frame cameras or other kinds of cameras can be used butone embodiment of the invention is to use a line-scan camera.

The present invention covers further embodiments with any combination offeatures from different embodiments described above. Reference signs inthe claims are provided merely as a clarifying example and shall not beconstrued as limiting the scope of the claims in any way. The presentinvention also covers the exact terms, features, values and ranges etc.in case these terms, features, values and ranges etc. are used inconjunction with terms such as about, around, generally, substantially,essentially, at least etc. (i.e., “about 3” shall also cover exactly 3or “substantial constant” shall also cover exactly constant). The terms“a”, “an”, “first”, “second” etc do not preclude a plurality.

1. An apparatus for determining density or number of living organisms ina flow, said apparatus comprising a channel for a flow of livingorganism, said channel comprises a flattened portion or lane made fromtransparent material a light source (4) for projecting light through astream of living organisms, said light source is positioned below theflattened channel or lane an outlet, and a computer wherein an opticaldevice (1) is positioned above and directed towards the flattenedchannel or lane, said optical device is positioned behind at least twomirrors, which reflect the light from the flattened channel or lane, andwherein the computer determines the density or amount of living organismbased on the amount of light reflected detected by the optical device.2. The method according to claim 1, wherein the optical device is acamera.
 3. The apparatus according to claim 1, wherein the camera is aline-scan camera.
 4. The apparatus according to claim 1, wherein the atleast two mirrors are first-contact mirrors.
 5. The apparatus accordingto claim 1, wherein the flattened portion or lane of the in-feed channelmade from transparent material has an open upper surface.
 6. Theapparatus according to claim 1, wherein the flattened portion or lane ofthe in-feed channel made from transparent material has a broadened lowersurface than the remaining part of the in-feed channel.
 7. The apparatusaccording to claim 1, wherein one or more of the channel for a flow oforganisms, the light source, the optical device and the outlet arepositioned within a housing.
 8. The apparatus according to claim 7,wherein the light source and/or the optical device are positioned withina separate housing below and above the channel for a flow of organismsrespectively.
 9. The apparatus according to claim 1, wherein the livingorganisms comprise fish, smolt, crustaceans, shellfish or other organismliving in freshwater or sea.
 10. A fish farm comprising an apparatus fordetermining density or number of living organisms in a flow , saidapparatus comprising a channel for a flow of living organism , saidchannel comprises a flattened channel or lane made from transparentmaterial a light source (4) for projecting light through a stream ofliving organisms, said light source is positioned below the flattenedchannel or lane an outlet, and a computer wherein an optical device (1)is positioned above and directed towards the flattened channel or lane,said optical device is positioned behind at least two mirrors, whichreflect the light from the flattened channel or lane, and wherein thecomputer determines the amount of living organism in a flow based on theamount of light reflected detected by the optical device.
 11. A methodfor determining density or number of living organisms in a flow , saidmethod comprising the steps of feeding a flow of living organism on achannel, said channel comprising a flattened channel or lane made fromtransparent material using a light source (4) for projecting lightthrough a stream of living organisms, said light source is positionedbelow the flattened channel or lane feeding the flow of living organismtrough an outlet, and wherein an optical device (1) is positioned aboveand directed towards the flattened channel or lane, said optical deviceis positioned behind at least two mirrors, which reflect the light fromthe flattened channel or lane, and wherein the computer determines theamount of living organism in a flow based on the amount of lightreflected detected by the optical device.
 12. The method according toclaim 8, wherein the living organisms comprise fish, smolt, crustaceans,shellfish or other organism living in freshwater or sea.